Impeovement -ih balance slide yalyes



:l e w n Minh tetes @anni ffice IMPROVEMENT IN BALANCE SLIDE VALVES JOHN LCHHEAD, OF SAN FRANCISCO, (lALlFR-NlA.

Letters .Patent No. 59,848, dated November 20, 1866.

SPECIFICATION.

TO ALL WHOM IT MAY GONCERN: l

' Beit known that I, JOHN LOCHHEAD, of San Francisco, in the county of San Francisco, and State of California, have invented a new and useful- Improvement in Balance Slide Valves; and I do hereby declare that the following Lis a full, clear, and exact description thereof, which will'enable others skilled in the art to I make and use the same, reference being had to the accompanying drawings forming part of this specification, in whichv Figure 1 represents a plan or top view of my invention, the cover of the steam-chest having been removed to expose the valve. i

Figure 2 is a vertical central section of the same.

Similar letters of reference indicate like parte. l This invention consists in a metal ring fitted into4 an opening in the valve and made of such a shape that said ring is kept up tight against the inner surface of the steam-chest cover by the pressure of the'steam alone,

. and without the aid of springs or other mechanical means'.- The ring is made of brass or other metal, which expands more than the cast ironl or other material, from which the body of the Valve is made, in such a man-ner that the expansion of the ring by the heat will make the vjoint between the same and the valve perfectly tight without the aid of packing.

A represents the face of the cylinder which forms the seat for the valve B. This valve is enclosed by the steam-chest C, and on its bach is fitted a ring I), which works steam tightaga-inst the inner surface of the steam-chest cover. A 4

Steam enters the valve-chest through a suitable opening in rits side, fand' it is admitted alternately to the opposite ends of the cylinder, through the ports a a; The exhaust steam passes off through the opening b in the valve, and through the ring D, and, exhaust pipe or opening c.

In the back of the valve is turned a groove, ci, to receive India-rubber or other suitable packing, which will keep the ring D up tight against the inner surface of the steam-chest cover if no steam is on. When steam is on, or if the engine is in operation, the exhaust steam passing up through the opening b of thevvalve, strikes the overhanging edge or 'ilange e of the ring, :and presses the same up tight against the inner surface of the steam:- chest cover. 4 i A A The ring, D, is made of brass, and ground into the valve, which is made of cast iron. By grinding the ring in its seat, it becomes a trie too small, and when it is cold it does not makea tight joint with the valve. But

as soon as the steam comes in contact with it, it heats andexpands so as to render the joint tight, and toprevent the escape of steam. This effect is produced bymaking the ring of brass or some other metal which expands more by heat than the cast iron or other material from which the valve i's made. p

I do not claim, as my invention, a slide valve composed of two-parts, working in opposite directions against the back of the steam-chest, and face of the cylinder,- and admitting steam in the centre, but what I claim as new, and desire to secure by Letters Patent, isy V The overhanging edge or liange e, 4of the ring D, in combination with the opening b, in the valve B, and with'the inner surface of thesteam-chest cover constructed and operating substantially as, and for the purpose described.

The above specification of my invention signed by me this 9th day of May, 1866.

JOHN LOGHHEAD.

Witnesses :5

G. A. MATHIEU, 

